Activating hierarchically hortensia-like CoAl layered double hydroxides by alkaline etching and anion modulation strategies for the efficient oxygen evolution reaction.

It is highly desirable to design and develop low-cost and Earth-abundant non-noble-metal electrocatalysts for the efficient and durable oxygen evolution reaction (OER) under alkaline conditions. Herein, hierarchically porous hortensia-like CoAl hydroxysulfide is converted from CoAl layered double hydroxides via alkaline etching and sulfuration strategies as an efficient electrocatalyst for the OER. In 1 M KOH, this electrode requires a low overpotential of 270 mV to drive the current density of 10 mA cm-2, with a small Tafel slope of 63 mV dec-1. Furthermore, it also possesses remarkably high stability with its activity being maintained at a stable overpotential of 10 mA cm-2 after testing for 26 h. Our work provides a promising cost-effective OER catalyst for large-scale electrochemical applications.